An endoscope conventionally comprises an elongated tubular shaft, rigid or flexible, having a video camera and/or fiber optic lens assembly at its distal end. The shaft is connected to a handle and viewing is made possible via an external screen. Various surgical tools may be inserted through a working channel in the endoscope for performing different surgical procedures.
Endoscopes, such as colonoscopes, that are currently being used typically have a front camera for viewing the internal organ, such as the colon, an illuminator, a fluid injector for cleaning the camera lens, and a working channel for insertion of surgical tools, for example, for removing polyps found in the colon. Often, endoscopes also have fluid injectors (“jet”) for cleaning a body cavity, such as the colon, into which they are inserted. The illuminators commonly used are fiber optics, which transmit light generated remotely, to the endoscope tip section.
The inside of internal organs such as the stomach, colon or cecum is generally reddish. As a result, when internal organs are observed using an endoscope without having appropriate color adjustment of picture image or video signals, the captured color images and videos carry a substantially reddish hue. In a conventional endoscope, in order to prevent this problem, a white balance adjustment is carried out; that is, values, factors or coefficients for making the intensity of the picture image or video signals for three primary colors such as red (R), green (G) and blue (B) equal, are applied to the video signal generated from a camera. In addition, white balance adjustment is also performed to make the intensity of the picture image or video signals for four additional colors, such as yellow (Ye), cyan (Cy), magenta (Mg), and green (G), equal for charge coupled device (CCD) sensor based processes. Such values, factors, or coefficients are generated by imaging a reference white color object.
However, for a multi-viewing elements endoscope, all cameras need to be calibrated for white balance consistently and uniformly. There is thus a need in the art for enabling consistent and uniform white balance calibration of all viewing elements of a multi-viewing elements endoscope. There is also a need in the art for a novel and easy to use reference white object that exposes all viewing elements of a multi-viewing elements endoscope to the same reference white level for purposes of white balance calibration.